The present invention relates, in general, to a flexible coupling for rotating shafts and more particularly to a flexible coupling for rotating shafts to transmit a comparatively great amount of torque between rotating shafts even though the shafts may be slightly misaligned.
Mutual misalignment of the shafts can be axial misalignment, angular misalignment and displacement between the drive shaft and the driven shaft, that is, there are three kinds of such misalignment.
As couplings for rotating shafts operating in mutual misalignment, there have been used flexible couplings using rubber or metal springs as elastic bodies, and gear couplings and the like utilizing the sliding action of gears. However, the former couplings, that is, flexible couplings using rubber or the like as elastic bodies, can transmit only a comparatively small amount of torque for their size, making themselves unsuited as couplings for transmitting a great amount of torque. On the other hand, the latter couplings, that is, gear couplings tend to have the tooth faces subjected to wear or spalling to a serious degree after a comparatively short period of use, making it necessary to replace them, which is a great disadvantage. But the gear couplings can transmit a great amount of torque for their size, and therefore, they are used widely as flexible couplings for rolling mills in steel plants or the like.
As mentioned above, the gear couplings are subject to reduced performance due to unavoidable wear, particularly when they are rotated at high speed, but there are no substitutes therefore and hence the above mentioned gear couplings must be used at the present time.
In order to solve the above-described problem, the inventor of the present invention has developed (U.S. Patent application Ser. No. 549,036 filed Feb. 11, 1975) a flexible coupling having a new structure for transmitting a great amount of torque (say 3,000 kg-m) for use in driving rolls of rolling mills. Said flexible coupling can transmit a great amount of torque for its size, without reduced performance due to wear such as occurs with the gear couplings, which is a great advantage.
On the other hand, for rollers of the roller table of a rolling mill there have been used flexible coupling for transmitting somewhat smaller amount of torque than the above-described flexible coupling for transmitting a great amount of torque; and for machine tools, pumps, compressors and other driving systems, there have been used flexible couplings for transmitting a comparatively low torque. Also in these fields of application, gear couplings have also been used as flexible couplings, resulting in the above-described trouble. Sometimes there are used disk couplings, which, however, are inferior in strength and are required to be machined with higher accuracy. For the inspection and maintenance of the rotating shaft system, the drive shaft and the driven shaft of the coupling may sometimes be separated for repairing or replacement of the coupling. Therefore, the down-time for repairing or replacement is required to be as short as possible for flexible couplings, in order to carry out speedy inspection and maintanence.